Optimal Time Allocation for Full-Duplex Wireless-Powered IoT Networks with Unmanned Aerial Vehicle

This paper investigates the rotary-wing unmanned aerial vehicle (UAV)-aided full-duplex wireless powered Internet-of-Things (IoT) networks, in which a rotary-wing UAV equipped with a full-duplex hybrid access point (HAP) serves multiple sparsely distributed energy constrained IoT sensors. The UAV broadcasts energy while flying and hovering. On the other hand, the UAV collects information while hovering. It is assumed that the transmission range of the UAV is limited and the sensors are sparsely distributed in the IoT networks. Thus, the energy broadcasted from the UAV is only available for the adjacent sensor. Here, we propose a new line model for UAV-aided IoT networks. With the proposed line model, we investigate the optimal time allocation to maximize the network throughput subject to a total time constant and a UAV maximum flight speed. The formulated throughput maximization problem is proved to be a convex optimization problem and the optimal solution is obtained by the mutual coupling of the convex optimization conditions. We further propose a simple algorithm under a specific condition. Finally, the numerical results verify that the performance achieved by the proposed optimal time allocation scheme outperforms the existing time allocation schemes. The maximum communication distance of the UAV at different heights and different transmission powers can be obtained through the comparison of algorithms.